I have created a child theme for Dokan theme. Is it possible for you guys to provide a accurate simple coding for child theme about translation. So, I can translate through the child theme and the translation will rewrite both parent theme and child theme's strings? And for saving the .mo and po. file in the child theme/language folder, the child theme will pick up and load it.

I have download the .mo and .po file for Dokan's translation project page, followed the instruction. I past them into my own child theme/language folder. After change the language setting from backend, the website does not pick up the translation.

If you have downloaded the .mo or .po file from Dokan plugin translation project then you have to place the file into the language folder of Dokan plugin. You can read this documentation- http://docs.wedevs.com/translate-dokan-plugin/.

If you have download the translation file for the plugin then no need to translate the theme. No need to put the language file for the theme. Just download the plugin translation file and put the file in the language folder of Dokan plugin. You have to follow the process which mentioned in the doc.